In rewatching 4x06 - Into the Fire, I find it kinda amazing at just how wrong Jeremiah was in 3x19 - Grey 17 Is Missing.

In 3x19, Jeremiah talks about how, on the second "evolution" of the universe - after a second big bang - the universe will know what it's doing. that everything the universe currently creates dies and that that's a serious design flaw and that the next time around, everything will be perfect.

In 4x06, Lorien says, in the beginning, everything was immortal - that the universe decided that immortality was overrated and decided to give people mortality so that they could more fully appreciate their lives.